Of course, your graphics card needs to support Vulkan in the first place, otherwise you'll still need to use 4gb patch.
Get DXVK from Github.com, then extract d3d9.dll and dxgi.dll to the directory where ra3_1.12.game is located.
For example: C:\Program Files\Steam\steamapps\common\Command and Conquer Red Alert 3\Data
Since DXVK transfers a portion of the non-essential active memory to the cache, the program still has enough memory to use even without LargeAddressAware.
It's mainly used to improve the performance of Vulkan cards under older DX, which is obviously a side effect of it. But it could make us think about giving up 4gb patch.
